scribner



(No Model.)

0. E. SGRIBN ER. TEST SYSTEM'FOR MULTIPLE SWITGHBOARDS.

No. 486,507. Pa-tented Nov. 22, 1892.

WITNESSES )Q INVENTOR WM/WWIQMQ 0h arZeSEScrihmer 4 fiw. BMWmW ATTYSUNITED STAT-ES PATENT FFICE.

- CHARLES-E. SCRIBNER, OF CHICAGO, ILLINOIS, ASSIGNOR TO THE WVESTERNELECTRIC COMPANY, OF SAME PLACE.

TEST SYSTEM FOR MULTIPLE SWITCHBOARDS.

SPECIFICATION forming part of Letters Patent No. 486,507, dated November22, 1892.

Application filed February 11, 1892. Serial No. 421.174. (lilo model.)

To all whom it may concern: ater of the line. In such acase the samecon- Be it known that I, CHARLES E. SORIBNER, tacts which perform thefunction of rendera citizen of the United States, residing at Chling theindividual annunciator unresponsive cago, in the county of Cook andState of Illiwhen a connection is made to line will per- 5 nois, haveinvented a certain new and useful form the additional function ofindicating the Improvement in Test Systems for Multiple idle or busycondition of the line when tested Switchboards, (Case No. 291,) of whichthe folwith the testing apparatus of my invention. lowing is a full,clear, concise, and exact de- The testing-plug may be one of the regularscription, referencebeing had to the accompaconnecting-plugs of anoperators telephone 1o nying drawing, forming a part of thisspecioutfit. The source of telephonic current may fication. be thesecondary coil of an induction-coil My invention relates tomultiple-switchwhose primary is in circuit with a battery board systemsfor telephone-exchanges. Its and a microphone lightly adjusted and keptobject is to provide means whereby it maybe in continuous slightvibration. The induced 15 certainly determined at any board whethercurrent in the secondary of the'induction-coil a line is already in useat some other board then finds circuit through the telephone-reor not,said means being distinct and separate ceiver in parallel with it andproduces a confrom the line-circuits. tinuous rustling noise therein.Thus to an Myinventioncomprisescontact-pieces upon operator testing aline the cessation of the 20 the different jacks of the line, adapted tobe sound in her telephone indicates that the line crossed together by asuitable contact-piece is already in use at some other switchboard. uponthe connecting-plug, corresponding con- My invention is illustrated inthe accomtact-pieces upon the different jacks being conpanying drawing,wherein I have shown it in nected together, and novel means fordeterconnection with a multiple-switchboard sys- 2 5 mining at anyspring-jack when the said contern in which a retardatioircoil isincluded tact-pieces are short-circuited at some other with theindividual annunciator in a branch jack. Said means consists of atesting-plug circuit between the two sides of the telephonehaving twocontact-pieces which are adapted -line, the annunciator beingshort-circuited to make contact with the said contact-pieces when aconnection is made to a line. 30 of the spring-jack, atelephone-receiver in a In the drawing two telephone sub-stationscircuit between the two contact-pieces of the l and 2 are shownconnected each with two testing-plug, and a source of telephonicunspring-jacks upon two sections of switchboard dulatory current in aparallel circuit with the and with individual annunciator upon onetelephone. This source of telephonic unduof the boards. The two linesare shown in 5 5 latory current will then normally create a connectionfor communication through a continuous and preferably slightdisturbcord-circuit of well-known type equipped with ance in thetelephone-receiver; but the curmy testing apparatus. Asecondcord-circuit rent will be wholly shunted from the teleis shown, one ofits connecting-plugs being phone when the testing-plug is inserted intoplaced in position for testing one of the lines. 0 40 the spring-jack ofa line already in use The apparatus at the sub-station 1 is of thethrough the contact-pieces of thetesting-plug, ordinary character,consisting of a callingcorresponding contact-pieces of thespringgenerator at and a call-bell a in a branch jack tested,and thecross connection between from one side of. line b, atelephonetransmitthe contact-pieces of the jack in which a conter a anda receiver a in another branch 5 5 necting-plug is present. from thesame side of line, and a gravity- My improved testing system isespecially switch 6%, connected to the other side of line adapted foruse in connection with a mulb, adapted toconnect either the callingaptiple-switchboard system in which contacts paratus orthe telephoneapparatus in the lineupon the spring-jacks are provided, adaptedcircuit, according to the position of the switch. too 50 to beshort-circuited to shunt or otherwise The linesb I) extend to anexchange, where render inoperative the individual annuncithey areconnected to line-springs one, re-

spectively, of the two spring-jacks d d upon two sections of multipleswitchboard e 6. An individual annunciatorf of ordinary construction anda retardation-coil 9, also of wellknown character, are included in aloop joining the two sides of line I) h. The spring: jacks are providedwith additional contactpieces or test-rings h, which are connectedtogether and by a conductor to a loop including the retardation-coil andthe individual annunciator at a point midway between them. Theconnecting-plug t is of the ordinary twopart type, having tip it, makingconnection with the line-spring c, and sleeve making contact with theline-spring c, which is made longer for that purpose. The extracontactpiece h also makes contactwith the sleeve 70 ofplug 2', wherebylonger line-spring c and-- the piece h are crossed togetherawhenwtheplugis inserted into the spring-jack.- circuit connections aresodisposedthah the, individual annunciator f is;short-circuited, whenthe line-spring c and the piece h are thus crossed together.Theapparatus and disposition of the circuits of sub-station2 is similar.to that of sub-station 1, the, line b be: ing continued through earthinstead of a complete metallic conductor. Its individual annunciator isplaced upon another switch:- board a. Like contact-piecesof the twoplugsof a pair are connected together by conducts orsin the "usual way,calling-keysnbei-ng in.- cluded, in these conductors, each; adaptedtodisconnectboth contact pieces of one. of the plugs from ,those of theotherand to connect them to wires m m,-forming the terminals of acallinggenerator 01, whereby call signals may be sent to any line. A.clearingout annunciator 0 is placed in a bridgeconnection between thedifferentconductors joining the;

two: plugs. A listening-keyp is provided,

adapted to connect the terminals of a tele-i phone-set-q to thedifferentconductors orcordstrands in the usual manner when :itsplungeris depressed. The secondary r of the induction-coil r is placed in aparallel circuit with the telephone-set q. The'iprimaryv-r of thisinduction-coil is included inlcircuit with a battery .9 and a microphonet, which is ad-; justedlightly and kept in continuous slight vibration.

I willnowexplaiu the operation of the sys: tem shown, givingspecialattention to the operation of testing bymy invention to determine whether a line is alreadyin use ornot.

Suppose, for example, that subscriber at sub-station 1 wishes tocommunicate withsu-b scriber-at substation 2. He operateshiscallinggenerator a and the switch, a being down, sends a current overthe lines b 12', which erated, attracting the attention of theoperartoratthe board 6', whereon it is situated to 1311003111. v The operatorthen-inserts one con: meeting-plug 'i of her pair into the jack d'.'

The

A local short circuit is now closed about the individual annunciator f,which may be traced from one side of that annunciator by the branch ofline b to the line-spring c of jack d, thence to the sleeve 70 of theplug '1', thence to the extra contact-piece or test-ring h of the jack,thence returning to theannunciator f. Hence any subsequentcalling-current sent over the lines b Z1 will be wholly shunted from theannunciatorf, which will therefore be unresponsive. The telephoniccurrent of lines I) b will not, however, be shunted through the coil 9on account of its high self-induction. The operator having thusestablished a connection between her cord-circuit and the calling line,depresses the plunger of her'listening-key p, as is shown in the uppercord-circuit at boarde, thereby connecting her telephone set in a loopwith the lines I) 1).

Having learned the connection desired, she proceeds to test the linecalled for. This-she does by inserting'the other connecting-plug 7; ofher pair a slight distance into the jack 01 0f the line called for atherboard until the tip of the plug makes--- contact with the longerline-spring of that:

jack, at the same time fixing her attention upon the faint rustlingnoisein hertelcphone. The plugt' at her board 6 is shown in position formaking sucha test of .the jack d of lines to station 2. It now the linetested be in use,'as is actually theoasein the drawings the secondary. rof induction-coil a" will be provided with a short circuit through onespring 0 of the jack d thence to conductor 1) to theline-spring-c' ofjack d to the sleeve 'kof the plug in that jack, thence to the testringJareturuing to 'test'ring h of jack d thence to the sleeve of plug 1)?through the ICC other-side. of listening-key" p to the; other- 4terminal of coil 9. The telephonic current from the induction-coil r isthuswholly shunted from the telephone set (1, producing complete silencetherein, thus indicating to the operator testing that the line tested isal-t ready in use at some otherswitchboard. If the line tested were notin use, a circuit would still exist from the tip to the sleeve of thetestplug, but would contain the coil of the elec-- tro magnet of theannunciator f of the line tested, which, being ofhigh resistance andself-induction,would not formany appreciable shunt to the telephone set,and hence would not materially reduce the noise in the tele-- phone.Thus-a complete disappearance of noiseiin thetelephone of thetesting-operator is a certain indication thattheline tested is alreadyin use. It will be noted that thistest is effected without disturbingthecondition of the, line tested andwithout at any time attachlnga groundorvcommon connection to either'the line or the toperators-outfit.

Assume that the operator atboard e finds linesto station2 not in use.She then inserts the other plug t of her pair into the jack The twosub-stations are thus looped into a continuous circuit, which may betraced from station 1 over the lines b b to the line-springs c c of jackd, thence to the corresponding contacts of plug '11, thence through theringing keys ll to the similar contacts of the plug 2, thence to thecorresponding contacts of the jack (Z and over the lines 19 b tosub-station 2. The operators telephone q is in a bridge connectionbetween the two sides of this circuit. The operator now depresses theplunger of ringing-key Z, thus connecting the two contact-pieces of theplug 11' to the two poles m m of the calling-generatorn, thereby sending a calling-signal to the sub-station 2. llaving assured herself thatthe subscribers at station 1 and 2 are in communication, she allows theplunger of listening-key p to rise, thus disconnecting her telephoneset. When the communicating subscribers have completed theirconversation, one of themfor example, subscriber at station 1-may send aclearing-out or disconnection signal. This current will find circuit tothe line-springs cc of jack d, thence through the cord-circuit to theclearing-out annunciator 0, which will thus be operated and willindicate the disconnection-signal to the attendant. An inconsiderableportion of the signaling-current will find circuit through theretardation-coil g; but none can by any possibility operate theindividual annunciator f of either of the connected lines.

Many other circuits for multiple switchboards have been devised to whichmy invention is equally applicable. I do not deem it necessary todescribe these systems further, since the application of my inventionthereto may be readily made by any one skilled in the art. I do notlimit myself to the employment of an inductioncoil r as a source ofundulatory current or to the vibrating microphone 15 to induce suchcurrent. Any other source of slight telephonic current or current ofrapid pulsation or alternation may be employed in connection with theoperators telephone set in the manner I have described. Moreover, it isnot essential that the operators telephone be employed as a responsivedevice. Other appliances adapted to give an audible or visual responseupon the cessation of current through them may be employed in place ofthe telephone set q, and a source of current suitable to the particularresponsive device may be employed. Many modifications of my inventionmay thus be constructed without departing from the spirit thereof.

Having thus described my invention and the mode of operation thereof,Iclaim as new and desire to secure by Letters Patent- 1. In a testingsystem for multiple switchboards, the combination, with a device adaptedto give a suitable response upon cessation of current through it, of asource of electricity in a parallel circuit therewith and contactpiecesconstituting terminals of said parallel branch circuits, adapted to beapplied to the contact-pieces of a spring-jack, whereby it may bedetermined whether the said contactpieces of the spring-jack areshortcircuited or not, substantially as described.

2. The combination,with a group of springjacks, each having twocontact-pieces adapted to be crossed together by a connecting-plugplaced therein, like contact-pieces of all the spring-jacks beingconnected together, of a testing-pl ug having two contact-pieces adaptedto be applied to the two contact-pieces of a spring-jack, and a sourceof electric current and a responsive device adapted to give a responseupon the cessation of current therethrongh in parallel circuits betweenthe two contact-pieces of the plug, substantially as described.

3. The combination, with spring-jacks, each having two contact -piecesadapted to be crossed together when connection is made thereto, likecontacts of the different springjacks being connected together, of atestingplug having contacts adapted to be applied to the contact-piecesof a spring-jack and a source of telephonic undulatory current, and atelephon e-reeeiver in parallel circuits, Whose terminals are connectedto the two contactpieces of the testing-plug, respectively,substantially as described.

4:. In combination with 'a telephone-line circuit extending from asub-station to a central station'and connected with spring-jacks at thecentral station, each having two linesprings and a test-ring, aconnecting-plug adapted to be inserted into any spring-jack having twocontact-pieces, one adapted to make contact with one of the line-springsand the other adapted to cross together the other line-spring and thetest-ring of the jack, a testing-p111 g having two contact-piecesadapted to be applied to the test-ring and to that line-spring which isadapted to be crossed with the test-ring, respectively, and a source oftelephonic undulatory current, and a telephone-receiver in parallelbranches, whose terminals are connected to the two contactpieces of thetesting-plug, respectively, substantially as described.

In witness whereof I hereunto subscribe my name this 30th day ofJanuary, A. D. 1892.

CHARLES E. SORIBNER.

Witnesses:

FRANK R. MOBERTY, GEORGE L. ORAGG.

